Flint's (silica) medicinal use is limited to homeopathy. Minute doses are prescribed for patients with conditions accompanied by excessive sweating, weakness, and extreme sensitivity to cold. For homeopathic use silica powder is mixed with sodium carbonate through a pharmaceutical process of dry substance dilution. Silica is mainly used for undernourishment that leads to a weakened immune system and recurrent infections, for example, colds, flu, and ear infections. It is also effective for skin and bone complaints, such as an unhealthy complexion accompanied by acne, weak nails surrounded by hard skin, slow-to-heal fractures, slow bone growth, and fontanels that are slow to close in babies. It is also good for expelling splinters from the tissues. Nervous system problems, for example, an inability to expel stools so that they slip back into the rectum, and migraines, where the pain starts at the back of the head and extends over one eye, are helped by Silica. It is also given for glue ear (fluid in the middle ear); chronic phlegm; profuse sweating; and sleep that is disturbed by stress and overwork.